A multifunctional ethology device for fish comprises a circular water tank which is internally divided into a plurality of swimming lanes, the bottom of the circular water tank is provided with a water outlet, an annular water pipe is erected on the inner wall of the circular water tank, a water inlet of the annular water pipe is communicated with a water outlet pipe of a circulating variable frequency water pump, water outlets of the annular water pipe are communicated with a vertical water pipe outside the water tank, a plurality of water outlets are arranged on the annular water pipe, each water outlet is externally connected with a branch water outlet pipe, the pipe wall of the branch water outlet pipe is uniformly provided with a plurality of horizontally-distributed small holes matching with the swimming lanes, the upper edge of each detachable annular diaphragm is provided with a plurality of drain triangular holes, and a lamp strip is arranged on the annular water pipe to provide uniform illumination. The multifunctional ethology device for fish can meet various research requirements on fish ethology, performs various ethological experiments and is applicable to fish with different specifications, so that the water flow self-circulation can be realized, the manpower and financial resources are saved, and the overall utilization ratio is high.